Household detergents causing eutrophication in freshwater ecosystems

Abstract

In the present study, the impact of some selected household detergents has been studied on the growth behavior and development of two freshwater duckweeds, namely Lemna minor and Spirodela polyrrhiza. The growth responses of these selected free-floating duckweeds to varying concentrations of Surf Excel (the most commonly used detergent) have been studied with special reference to varying temperature and pH. There were three predominant types of growth pattern of both the selected duckweeds treated with 36 selected detergents. Some of the detergents increased the growth of the two duckweeds in almost logarithmic progression showing increase in growth with increasing concentration (10-50 ppm). A few detergents increased growth of both the selected duckweeds to a certain level of detergent concentration and then the growth became stationary with further increase in detergent concentration. In the third type of response, the duckweed growth initially increased in response to a certain level of detergent concentration and declined at higher detergent concentration. It was inferred from the observations that detergents play important role in promoting the growth of duckweeds. Out of 36 detergents studied, certain detergents effectively promoted the growth of duckweeds even in low concentration. Certain brands of detergents resulted in consistent increase in the growth with increasing concentration. The temperature effectively modified the duckweed response to the detergent. The cooler water medium had lesser degree of eutrophication than the moderately warm water medium. Not the phosphorus content alone, but the water quality (turbidity, pH, nutrient concentration, and dissolved oxygen) modified by the detergent aggravated the problem of eutrophication. Therefore, the water bodies receiving acids from any source in addition to detergent are more likely to show a greater degree of eutrophication than a body receiving detergent without acids.